utils

README

package utils

Contents

• Overview
• Requirements
• Installation
• Package: reflect
  • Function: EstimatePayloadOf
    • Supported Types
    • Performance
    • Use Case
    • Examples
• Roadmap
• License

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📋 Overview

The utils module provides a set of lightweight, focused utility packages designed to extend Go's standard library with commonly needed functionality. These packages follow Go's philosophy of simplicity and efficiency, offering well-tested solutions for everyday development challenges.

For full documentation, see https://pkg.go.dev/github.com/lif0/pkg/utils.

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⚙️ Requirements

• Go 1.19 or higher

📦 Installation

To add this package to your project, use go get:

go get github.com/lif0/pkg/utils@latest

Import the reflect extension in your code:

import "github.com/lif0/pkg/utils/reflect"

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📚 Package reflect

Function: EstimatePayloadOf

func EstimatePayloadOf(v any) int

Returns an approximate payload size (in bytes) of the given value. It is designed for efficiency and is allocation-free for supported types

⚠️ Return Value and Errors

• Returns the estimated size in bytes for supported types.
• Returns reflect.ErrFailEstimatePayload = -1 if the type is not supported or cannot be estimated.

Performance Notes

This function performs zero allocations and runs with 0 B/op for supported types. See benchmark

• No memory allocations — 0 B/op for all primitive types.
• Reflection is used only for arrays and structs:
  • Supports any primitive types in arrays.
  • Supports only time.Time{} for structs.
• For arrays [N]T, prefer passing *[N]T to avoid value copying.

Check:

• Benchmarks
• Tests

✅ Supported Types

Scalar types (and pointers to them):

• int, int8, int16, int32 (rune), int64
• uint, uint8 (byte), uint16, uint32, uint64, uintptr
• float32, float64
• complex64, complex128
• bool
• string
• time.Time, time.Duration

Containers:

• []T, []*T, *[]T, *[]*T — slices
• [N]T, *[N]T, [N]*T, *[N]*T — arrays (via reflection)

For pointers and slices, nil is treated as zero-size.
For string and []string, the actual content size is summed.

If the type is not supported, the function returns reflect.ErrFailEstimatePayload(-1).

💡 Use Case

Calculate request/response sizes for logging or monitoring, such as writing to a span in a database provider library.

🧪 Examples

Estimate an int value:

var v int = 42
n := EstimatePayloadOf(v)
// n == 8 on 64-bit systems

Estimate a string:

s := EstimatePayloadOf("hello")
// s == 5 (len("hello"))

Estimate a slice of strings:

names := []string{"John", "Doe"}
size := EstimatePayloadOf(names)
// size == len("John") + len("Doe") == 4 + 3 == 7

Estimate a slice with nil strings:

names := []string{"John", nil}
size := EstimatePayloadOf(names)
// size == len("John") + len("") == 4 + 0 == 4

Estimate a struct:

type User struct {
    ID   int64
    Name string
}
u := User{ID: 123, Name: "Alice"}
size := EstimatePayloadOf(u)
// size == reflect.ErrFailEstimatePayload(-1), because it is a custom struct

Estimate an array (pass by pointer for performance):

var arr [1000]int32
size := EstimatePayloadOf(&arr)
// size == 1000 * 4 == 4000

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🗺️ Roadmap

The future direction of this package is community-driven! Ideas and contributions are highly welcome.

☹️ No idea

Contributions and ideas are welcome! 🤗

Contributions: Feel free to open an Issue to discuss a new idea or a Pull Request to implement it! 🤗

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📄 License

MIT

Documentation

Overview

Package utils provides a collection of utility functions for Go applications.